It sounds simple. But more than 60% of adults in England are overweight or obese. Our lifestyles see many of us eating more calories than we need and not doing enough physical activity.

Do you recognise some of the causes of your weight gain in any of the following?

Food that's labelled 'low-fat'

Lots of foods in the supermarkets today are labelled "low-fat". But there's a catch, explains nutrition scientist Lisa Miles. "In some cases, low-fat foods contain high levels of sugar. High sugar foods can also contain lots of calories and so contribute to weight gain."

What can I do?"Read the labels," says Miles. "You need to look at the overall energy and calories. Although a food may have a reduced amount of fat, it may still have the same amount of calories." A food labelled "low-fat" may still contain more calories than an alternative. For example, a "low-fat" muffin may contain more calories than a currant bun. Find more healthy food alternatives in Healthy food swaps.

Stress

It can be easy to reach for a sugary pick-me-up when stressed. Do this often, and you may put on weight.

What can I do?
"Snack on fruit and veg and other low-calorie options such as plain popcorn, crackers and rice cakes," says dietitian Anna Suckling. And find ways to cope with stress that don't involve food. "Exercise helps promote mental wellbeing through the release of endorphins, which help to combat stress," explains Suckling.

Television

Watching a lot of television can contribute to an inactive lifestyle, and many of us consume calories we don't need while watching TV. Suckling explains: "People often find that while sitting in front of the TV, they snack on energy-dense foods such as crisps and chocolate."

What can I do?
"If you're worried about your weight, take part in more daily physical activity, if your health permits," says Suckling. "Try walking to work, school or the shops and spend less time in front of the TV. Don't forget that you can do an activity while watching the TV, such as using an exercise bike." For more ideas, see Get active your way.

Your medicine cabinet

Weight gain is a common side effect of many drugs. The most common drugs that can cause weight gain are steroids, antipsychotic drugs, and insulin, among others.

Late nights

Some research suggests that a lack of sleep can contribute to weight gain. Dr Neil Stanley, sleep expert at the Norfolk and Norwich University Hospital, says, "There seems to be a strong link between lack of sleep and putting on weight."

What can I do?Simple: get more sleep. "You feel wonderful when you wake up from a good night's sleep," says Dr Stanley. "In these modern times, we regard sleep as a waste of time. But sleep is central to good physical and mental health." If you have trouble sleeping, get advice in Living with insomnia.

Good manners

In an ideal world, friends and family would encourage you to lose extra weight. In reality, they sometimes push you to eat more high-calorie food. Is it rude not to finish that double helping of chocolate cake at a dinner party? Sometimes it feels that way.

What can I do?
Learn to say "no, thank you" and stick with it. Get used to the idea that it's OK to leave food on your plate. Soon, friends and family will come to respect your decisions.

Portion sizes

Over the last few decades, the size of portions served in restaurants and supermarket packages has increased. A study by the World Cancer Research Fund (WCRF) found that burgers, for example, have doubled in size since 1980. Not surprisingly, research shows that when we're given a larger portion we tend to eat more.

What can I do?
Coping with larger portion sizes is a matter of stopping when you feel full. Eat slowly and you'll have a better chance of avoiding that over-stuffed feeling. At home, serve yourself a smaller portion and think about whether you really want a second helping. Avoid supersizing portions when eating out. You can control portion size and save money when you cook fresh, healthy meals at home.